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Do Now:

Objective: SWBAT use the evidence of livor mortis , rigor mortis, and algor mortis to calculate the approximate time of death. Do Now:. Review Game. Purpose: Be able to guess your word(s) by using only minimal clues Round 1: charades (no talking) Round 2: one word

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Do Now:

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  1. Objective: SWBAT use the evidence of livor mortis, rigor mortis, and algor mortis to calculate the approximate time of death Do Now:

  2. Review Game • Purpose: Be able to guess your word(s) by using only minimal clues • Round 1: charades (no talking) • Round 2: one word • Round 3: definition or example

  3. Introducing the Mortis Brothers The Chemistry, Math and Biology of Death

  4. Rigor Mortis • Skeletal muscles partially contract • Joints stiffen, lock in place • Onset is 10 minutes to several hours • Rapid cooling can delay it • Lasts up to 72 hours

  5. Chemistry of Rigor Mortis • Living muscle cells use oxygen to burn glycogen • After death no oxygen—anaerobic glycosis makes lactic and pyruvic acids • pH falls as acidity increases • Acid promotes a reaction between actin and myosin which work together to contract the muscle • Muscle shortens until all ATP and acetylcholine is used up

  6. Exit Ticket In 4-5 full, complete sentences Give a definition of rigor mortis, livor mortis, and algor mortis. How does this relate to calculating the manner, cause, mechanism or time of death. BRING YOUR CALCULATORS FOR THURSDAY!!!

  7. Muscle Contraction

  8. Ca and ATP Ratchet the Fibers

  9. End of Rigor Mortis • The muscles relax when the body starts to decompose and the fibers begin to break down • Intracellular digestive enzymes are released from the lysosomes as the cells begin to disintegrate, destroying the muscle fibers (autolysis) • Meat is more tender after rigor mortis has passed (Aged Beef?)

  10. Livor Mortis • Heart stops beating which had been mixing blood • Red blood cells are denser so they sink • Maroon to blue color develops at lowest points • Visible 30 minutes-2 hours after death • Tells you if the body was moved.

  11. Livor Mortis • Soon after death, blood is still in vessels, so pressure on an area pushes the bood out— • get blanching up to approximately 4 hours after death • As time goes on blood vessels break down as do blood cells and hemoglobin break down pigment moves out into the tissues • No more blanching • Pressure or constrictive clothing prevents blood from pooling locally • Contact pallor

  12. Livor Mortis

  13. Livor Mortis • After death cells release enzyme (fibrinolysins) that prevents clotting • Blood in body stays liquid after death • Permanently won’t clot 30-60 minutes after death

  14. Algor Mortis • Body cools by • Radiation • (the higher the body temperature the more heat lost) • Conduction depends on surface contact • faster if in water because enhanced contact • Convection • Wind cools faster • Rate of cooling of body after death • 1.5 °F per hour under “normal conditions” • No real conditions are “normal”

  15. Algor Mortis • Ambient temperature • Newton’s Law of Cooling • T is body temperature, t is time • The bigger the temperature difference, the faster the cooling rate • Outdoors, temperature varies a lot—must correct formula by varying Tambient

  16. Algor Mortis • If ambient temperature is constant, Newton’s Law of Cooling is easy to solve • Measure temperature at two different times without moving the body to find k

  17. Algor Mortis

  18. Algor Mortis • Clothing • Insulates body from heat loss • Obesity • Fat insulates, temperature falls more slowly • Ratio of surface area to volume • Children, thin people cool faster • In water? • Cooling is faster since water is a better conductor of heat than air

  19. Algor Mortis • New issue • Is there a plateau before body temperature starts to fall after death? • May be up to several hours • Anaerobic cellular chemistry continues after death • Cellular chemistry releases energy as heat

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